Apparatus for drying



Jan. 7, 1941. I s sMlTH 1 Re. 21,686

APPARATUS FOR DRYING Original Filed Aug. 2, 1955 2 sheets-Sheet l DRYING CHAMBER Ti. 1. V 69 Pusunsn 68 I VACUUM COOL ING WATER INVENTOR ATTORNEYS Jan. 7, .1941. F. 5. SMITH APPARATUS FOR DRYING Original Filed Aug. 2, 1935 2 Sheets-Sheet 2 FROM DRYING CHAMBER 6O FROM PURIFIER 69 R O T N E v Eunklin S. Smith r-QM ATIPBEEXS @ZLM Reissued Jan. 7, 1941 APPARATUS FOR DRYING Franklin 8. Smith, Bethany, Conn, auignor, by means assignments, to F. J. Stokes Machine Company, Philadelphia, Pa., a corporation of Pennsylvania Original No. 2,127,474, dated August 16, 1938, Se-

rial No. 84,313, AW 2, 1935.

Application for reissue August 3, 1940, Serial No. 351,078

8 Claims.

This invention relates to apparatus for drying.

One of the objects of this invention is to provide an apparatus for vacuum drying which is simple and practical in construction and eflicient and reliable in operation. Another object is to provide apparatus of the above nature which can be inexpensively manufactured and readily assembled. Another object is to provide apparatus of the above nature which operates with maximum efficiency in an inexpensive and simple manner. Another object is to provide apparatus of the above nature which is thoroughly dependable and amenable to a great variety of uses. Other objects will be in part ap arent and in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, arrangements of parts, and in the relation and order of each of the same to one or more of the others, all as will be illustratlvely described herein. and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings in which is shown a preferred embodiment of the mechanical features of my invention,

Figure 1 is a diagrammatic view of the several elements of my drying apparatus;

Figure 2 is a vertical section of the vacuum pump and oil reservoir shown in Figure 1; and

Figure 3 is a diagrammatic vertical section of a part of the purifier shown in Figure 1.

Similar reference characters refer to similar parts throughout the several views of the drawings.

As conducive to a clearer understanding of certain features of this invention, it may first be noted that vacuum drying systems depend in part for eilicient operation upon the lubricating and scaling properties of the oil used in the evacuating device in the system. Accordingly it is primarily important that such oil be kept in as pure and unadulterated condition as possible. Vacuum drying systems are notorious destroyers and wasters of oil mainly because the oil reconditioner incorporated therein is, in many instances, incapable of fulfilling its assigned duty. If these systems be made to utilize some type of settling tank wherein the adulterated oil runs through a. filter to separate the foreign solid particles from the oil and water and permit the I water to settle in the bottom of the tank, to be subsequently drained, the results are unsatisfactory. While some of the impurities would be separated in this manner, a large portion of them would still remain in the oil and be consequently reintroduced into the evacuator. As these impurities are constantly flowing into the evacuator with the oil, they are constantly being dispersed into the oil due to agitation by the evacuator. As the impurities consist of moisture and for- .eign particles, all the elements are present which upon working will cause emulsification of the oil and the moisture. Accordingly the evacuator functions also as a colloidal mill or homogenizer instead of functioning solely as a vacuum pump and the oil is impaired as a lubricating and sealing medium. As a settling tank or the like will not separate an emulsion, it would soon become necessary to drain oil the emulsified oil and introduce new and pure oil. Inasmuch as a large quantity of oil is used, this constant changing would not only entail considerable expense and interrupted operation, but also inconvenience and a problem of waste disposal. Furthermore, the

emulsifying action is considerably expedited due to the relatively high temperature of the impurities and moisture drawn into-the evacuator from the drying chamber. The heat tends to reduce the viscosity of the oil thus rendering it less effective as a sealing medium and more amenable to emulslflcation. One of the dominant objects of this invention is to provide a method and apparatus for a vacuum drying system wherein the above-noted conditions as well as many others are practically and efliciently rectifled.

With reference to Figure 1, there is generally indicated at 60 a drying chamber or the like which is preferably capable of maintaining a vacuum and in which may be deposited a mass of material 6| for drying. Chamber 60 is provided with an opening or port 60a which receives a pipe 62 which is suitably connected with a condenser generally indicated at 83 and extends therethrough to connect with a pipe 621: leading from the condenser. A pipe 82 communicates with the interior of condenser 83 and introduces cooling water therein from any convenient source 8| to surround pipe 62 and cool vapors passing therethrough. Another pipe 84 connects condenser 83 with a suitable waste drain 13 to provide an exhaust channel for the cooling water introduced into the condenser. Thus cool water completely surrounds and circulates about pipe 62 to reduce the temperature of moisture, gases, foreign particles and the like withdrawn from chamber ill.

Pipe 62a leads into a vacuum pump generally indicated at 63. Pump 63, the construction and operation of which will be more fully described .intoasumpllorthelike. large -nel'll1ihichconhectswithpumpl3bywayof Pref an overflowpipell connectschannel'll with sumpeignparticle'sfrommaterialilanddepositsth oilusedinp'umpllforlubrlcatingand possibleinordertoavoidemulsiflcationofthe oilanclitsconsequentimpairmentasalubricat-- apipe'llandareservoirlla.

toprovideaby-pass forsurplusoilinexcess of the quantity which reservoir Ila and pump 3 can accommodate. Preferably purifier 89 likewise hasan overflow pipe 40 connected to sump it to accommodate excess mixture which would otherwise overtax ,the capacity of the purifier.

Preferably pump 63 is provided with a cooling jacket, illustratively shown as a jacket Ila, which conneetsatoneendwithapipell connectedto water source "and at the other end with a ripe 18 connected to drain ll. Accordingly cool.

ingwateriromsourcell flowsthroughpipel'l, water jacket 11a, and pipe 18 to empty intowastedrain 13. Thus the heat engendered in pumpfl'by friction of moving parts. hlsh pressm'esandtheheatof the foreign particlesand moisture is rapidly and efliciently dissipated, the purposes and advantages of which will be more fully indicated hereinafter.

It may now be seen that the construction is unitary in character and that theseveral elements, namely the drier, the condenser, the vacuumpump,theoi1pump andthepuriiienare so combined as to produce a highly meritorious result due to their coaction, all as will be more specifically pointed out hereinafter.

Referring now tol'lgure 2 of the drawings, vacuummmpucomprisesabase l whichsupports an outmcasing or water jacket I which, withaninnerwall-orcaslng'l, enclosesaspace U through which cooling water may circulate.

.Walllalsocomprlsesa cylinderwallwhlchenclosesacylinderspacelinvvhichadriveshaft eccentrlcorcampart ll. Shaft.

lgsupportsan ll maybe suitably iournaled in the ends (not showniofthepump bodysand-isdriveninany convenient manner as for example by a tomotor'llmsurel). Camllmguremhasslidablyniountedthereabout apiston generally indicated at I! having acylindricalbodyportion llawhichhofluch aslneastobeintangentialcontactwiththe upwardlyintoa formedinpump "bythcupper andanysubstanceflowing P rt lld Just before piston l2 attains its highest position, port lid in arm lib is completely closed by pin ll, thus forming an eihcient mechanically operated suction valve.

The moisture, gases, and foreign particles thus drawn into cylinder 9 are expelled through a spring-biased-discharge valve, generally indicated at ll. Valve It comprises a port it formed in casing l and communicating with cylinder lavalve seat II, a sulderod |l,a valve spring is disposed about guide rod II and biasing seat ll toward a closed position, and chamber 20 inwhichtheguiderodandspringaredispose'd. A suitable housing or casing 2| receives the outer end of snide rod II and provides an abutment 22 against which spring ll bears in forcing the valve seat toward its closed position. channel Ila communicates with chamber 2| and isconnectedtopipelfl'igurel) leadlngto sump M. The pressure created in cylinder 9 r by the tangential movement of piston l2 therein forces valve block II from its seat against the action of spring ll to permit discharge of moisture, gases, foreign particles, and oil from cyl- A suitable inder I through port Ii, chamber 2., channel Ila, and pipe .(Flsure 1) into sump M.

In order to insure emcient operation of pump ll, cooling water is circulatedvthrough water Jacket 8, the water being introduced thro h an inlet la connected with pipe ll' from source II and escaping through anoutlet lb' connected withplpe'llleadingtowastedrainli. Reservoir "a is preferably located between purifier I! and pump 03. Pipe ll (Figure l) connects the reservoirtochannel l4 leadingfromthe purifierand a pipe lib (Figure 2) forms an outlet from the reservoir to pipe lib I provide a pipe lie and a pipe lid. Pipefllc connects with suitable ports (not shown) formed in both ends of pump it to provide 011 lines for lubricating and scaling 011 for pin l3 hollow arm lib. In a sub- 81,886 stantially similar manner, pipe 13d provides ade-.

quate oil for lubricating drive shaft l3 and cam l I and for both lubricating and sealing the bearing surfaces of piston l3 and cylinder wall I. In this manner an ample supply of oil is delivered to both ends of the pump and the risk of the pump running dry is obviated.

Thus it will be clear that I have provided a suitable pump capable of emcient operation even when subjected to repeated charges of slugs of moisture, uncondensed gases and foreign particles.

During the operation of the pump, the lubricating and sealing oil, used therein. comes into continuous contact and is mixed with the liquids, gases and foreign particles sucked out of the drying chamber. If no more than the oil and moisture were mixed together without any great amount of turbulence or worlnng, the oil might be purified by allowing the moisture to settle out and be drained of! in a settling tank. Even so, however.-all the moisture could not be thus removed and the oil would. rapidly lose its body and its sealing and lubricating properties would thus be lost. This would result in a decrease of vacuum pump efllciency as the pump has large areas continually in need of lubrication and sealing during the motion of the several moving parts. As the piston in the pump revolves at a high number of revolutions per minute, the oil and impurities are subjected to such great turbulenceand working that the resultant mixture is a sludge which will not readily separate into its component parts by setting. It follows that a portion of this sludge will be returned to the pump and will be worked again.

When there is a third agent, such as partiemulsify. Such working and consequent emulsification takes place when the several substances are forced repeatedly through small orifices or spaces such as between the piston and cylinder walls of the pump or any other contacting surfaces therein. It is, of course, impossible to settle out theoil in this event as the emulsion is stable and the oil is, therefore, useless for sealing or lubricating purposes.

In order to prevent the deterioration of the oil by emulsificatiom'the oil should be separated from the impurities immediately after leaving the pump and before a sludge can be formed. In order to carry out such separation or purification, I provide the centrifugal purifier 39 (Figures 1 and 3).

A portion of purifier 39 is diagrammatically illustrated in Figure 3 wherein pipe 33, leading from pump 36 and sump 63 (Figure 1),,empties into a reservoir 33 or the like suitably mounted in the top of the purifier. A pipe 3| connects with reservoir 33 and empties into a chamber 32 formed within a suitable separator bowl 33 rotatably mounted on a drive shaft 33. Shaft 33 may be driven through any suitable mechanism such as a countershaft and pulley, generally indicated at I3, by motor 19 and belts 13a and 131) (Figure 1).

Suitably disposed within bowl 35 (Figure 3) I preferably provide an element generally indicated at 33 comprising a substantially tubular portion 33a and a frusto-conical part 33b. Thus,

when properly positioned in bowl 35, element 33 sludge.

forms chamber 32 and with bottom of bowl 33 forms a passage 33.

Another element generally indicated at 31 is likewise disposed immovably within bowl 33 and is superimposed about portion 330 of element 33,

' thus forming a passage 33 with the top of bowl 33 and also a chamber 33 with the top of part 331: of element 33. Element 31 also forms apessage 33 with tubular portion 330, andv portion 331: forms still another e 3| with pipe 3|.

-Thus it will be seen that there is provided four passages, namely, inlet e 33 and the three outlet passages 33, 33. and 3|, the purpose and operation of which will be described hereinafter.

Suitably arranged above bowl 33. I provide a series of chambers, preferably three in number and generally indicated at 32. 33 and 33. Chamq ber 32 connects passage 3| and thus to chamber 32; chamber 32 also connects pipe 33 which leads to sump 33 (Figure 1) to accommodate surplus Chamber 33 connects e 33 and chamber 33 with pipe I3 which leads to oil reservoir 130 (Figure 1). Chamber 33 connects passage 33 with pipe-l2 which leads to waste drain 13 (Figure 1).

In operation the adulterated oil is pumped from sump 33 by pump 33 into reservoir 33 from which it flows through pipe 3| into chamber 32, thence through passage 33 into the separator bowl chamber 39. As the separator bowl is revolving at a high rate of speed, any substances introduced therein will be subjected to thecentrifugal force induced by the bowls rotation. As the mixture in chamber 39 consists of several substances having different specific gravities, the heavier substances are forced toward the periphery of the bowl to the disadvantage of the lighter substances which are displaced from the outer portions of the bowl and hence forced toward the center thereof. Thus the foreign particles, being the heaviest components of the mixture, are forced against the outer wall 33a of bowl 33 where they form into a sticky mud and are removed from the mixture accordingly. The water in the moisture, having the next highest specific gravity is forced into portion 390. of chamber 33. The pure oil, having the lowest specific gravity of any of the components of the mixture, thus accumulates in the inner portion of chamber 33 in a substantially unadulterated condition.

As more mixture flows into the bowl. the water in portion 390 is displaced and flows through passage 33 into chamber 33 and from there to waste drain I3 by way of pipe 12. The pure oil in chamber 39 is likewise displaced and flows through passage 33 into chamber 33 from which it flows into reservoir 15a through pipe 13. If

more mixture is introduced into the purifier than can be accommodated thereby, an overflow into sump 33 is provided by way of chamber 32, passage chamber 32 and pipe 33.

As the mud forming on wall 330 would eventually clog passage 33 and generally impede the operation of the purifier, bowl 35 is so constructed that it can be readily removed for cleaning. In order to clean the bowl it is, of course, necessary to stop the purifier but, in order that the operation of vacuum pump 33 be uninterrupted, reservoir 13a is of suificient capacity to store enough pure oil for the needs of the vacuum pump during the cleansing periods. Sump 33 is likewise of sufficient capacity to receive the mixture during such periods as pump 33 is shut down when the bowl is being cleaned. Thus it is not necessary of equaliywellutiiiaed-inotheriields.

Accordingly it will be seen that I have provided a vacuum drying system wherein the lubricating andsealingoilis'maintainedinapureandim- 'state with the result that the loss of oil successfully Asmanypos'si eembodimentsmaybemadeof above invention, without departing i'rom the tendency to give oil solids, moisture and gases during the drying process, an evacuating pump utilising a sealing lubricant, mans connected to said evacuating pump for supplying sealing lubricanttosaid wnmsaidevacuating'pumpbeing constructedsothatthesolidsandliquidstaken therein are mixed with and contaminate said lubricant, a sump, means for conveying said contaminated lubricant from said pump to said sump. separating means adapted to separate the lubricant from the solids and liquids, means for.

conveying said contaminated lubricant from said sump to said separating "means, and means for returning purified lubricant from said separating means to said lubricant supp y n means.

2. The combination with apparatus having a vacuous chamberfrom which solids, moisture and gases are drawn oil during evacuation thereof, of a rotary vacuum pump utilising a sealing lubricant,areservoirconnectedtosaidpumpforsupplying sealing lubricant thereto. said p mp being constructed so that the sealing lubricant rims throughthe-interiorthereofandmixeswith the solids and liquids drawn therein to form a sludge,

a sump, mans for conveying sludge from and vacuum pump to said sump, a centrifugal separator for separatinathe lubricant from the solids and liquids, mans including a circulating pump for conveying said sludge from said sump to said separator, common motor means for driving said vacuum pump, said circulating pump and said separator, and means for'returning purified lubricantirom'saidseparatortosaidreservoir.

3. The combination with apparatus having a vacuous chamber from which solids, moisture and gases are drawn of! during evacuation thereof, of evacuating mans utilising a sealing lubricant, a. storage tank connected to said evacuating mans for supplyin sealing lubricant to said evacuating means, said evacuating means being constructed sothatthesolidsandliquidstakenthereinare mixedwithsaidhrbricanttoformasludgea sump, a conduit for conveying sludge from said evacuatingmeanstosaidsumpsepai atingmeansadaptedto separate the lubricant from the solids and liquids, mans for continuouflyeonveyinr saidsiudgefromsaids'umptosaidseparating meanaandmeansforcontinuoualyreturnings'aid 'lubrioantfromsaidseparatingmeanstosaid the lubricant, mans including a circulating pump and connections therefor for continuously supplying lubricant i'rom said sump to said separator, and means including Pipe connections for em- -tinuouslyreturningpureoiitosaidreservoir.

macombinationaccordingtoclaimfiwherein the centrifugal separator must be removed at times for the purpose of cleaning, and-wherein said reservoir. and said sump have suflident capacity to supply adequate lubrication to said pump while said separator is being cleaned.-

7. The combination with apparatus having a vacuous chamber from which a condensabie vapor is drawn 01! during evacuation'thercof, a pump for evacuating said chamber having mdischarge port, a source of lubricant for lubricating and sealing said pump, means for continuously supplying lubricant from said source through the interior of said pump and the same at the discharge port ofsaid pump. said pump being operable to compress the vapor drawn from said chamber whereby a portion thereof is condensedandatleastapartoftheis mixed with the lubricant and is discharged from saidpumpintheiormofanemulsiomasumma conduit for conveying the emulsion and discharge gasesfromthedischargeportofsaidpumpto said sump, separating mean adapted to separate the condensate from the lubricant, means for ca:-

' tinuousiy conveying the emulsion from said sump to said separating means. and mans for returning the condensate-free lubricant tron: said separating means tosaid source of lubricant.

8. The combination with apparatus having a vacuous chamber from which water vapor is drawn of! during evacuation thereof, a pump for evacuating said chamber having a discharge port, a source of oil for lubricating and sealing said pump. means for continuously supplying lubricatingoil fromsaidsourcethroughtheinteriorof saidpuinpanddischargingthesameatthedischarge port of said pump, said pump being oper- I able to compress the vapor drawn from said chamber whereby a portion thereof is and a part-of the} condensate is mixed with the oil discharged from saidpump to form an emulsion, a sump, a conduit for conveying the unulsion-andgasesiromthedischargeportofsaid pump to said sump, a cmtrifugal separator, mans for continuomlyconveying the oil emulsioniromsaidsumptosaidcmtrifimalseparator,

and means forreturningthefreeoil from said separator-tosaidoilsource.

\ WS.SMITH. 

